Electric fuel pump



Aug. 15, 1939, J. B. WHITTED ELECTRIC FUEL PUMP Filed March 5, 1937 3Sheets-Sheet l llllll Aug. 15, 1939. J, B, wHmED 2,169,862

ELECTRIC FUEL PUMP Filed March 5, 1957 3 Sheets-Sheet 2 .23 30 123 J i f1 g l u "(9 J hi1 I" ms. I J 1} M111" "lb I i I I I 1/ 'u I I A y s I FE I i g I H I I 26 g8 i 18 34 M 1 2 7 we we )zfbr Z5 5 Jo/ve 5. Wlulfedfixwzom Patented Aug. 15, 1939 ELECTRIC FUEL PUMP John B. Whitted,Glencoe, Ill., assignor to Stewart-Warner Corporation, Chicago, 111., acorporation of Virginia Application March 5, 1937, Serial No. 129,108

14 Claims.

pump. In attempting to apply the conventional filter to the electricfuel pump disclosed in my said prior application, I found that theresults were unsatisfactory and that the efiiciency of my fuel pump wasmaterially decreased.

An object of my present invention is to provide a combination electricfuel pump and filter therefor which is eilicient and satisfactory inoperation.

Another-object of my invention is to provide a an electric fuel pumpwhich will operate satisfactorily at extremely low temperatures.

Another object of my invention is to provide an improved diaphragm foranelectric fuel pump.

Another object of my invention is to provide an improved motor circuitfor my electric fuel P p- Another object of my invention is to providean electric fuel pump which will operate satisfactorily and efficientlythroughout a wide range of voltage variation of the actuating current.

Another object of my invention is. to provide an electric fuel pumphaving improved means for supporting and protecting the operating parts.

Other objects and advantages will become apparent as the descriptionproceeds.

Referring to the drawings;

Figure 1 is a vertical end elevation of my im- I proved, electric fuelpump;

Figure 2 is a horizontal section taken on the line 2-2 of Figure 1;

Figure 3 is a vertical section taken on the line 3-3 of Figure 2;

Figure 4 is a view of my improved diaphragm;

Figure 5 is a section taken on the line" 5-5 of Figure 4;

i ure 6 is a horizontal section taken on the line 6-6 of Figure 1. Inthis section the valves are shown as removed; and v Figures '7, 8, 9,10, and 11 are diagrammatic views of the circuit arrangement of myimproved electric fuel pump as including a die-cast or drawn steelhousing It) provided with a pair of 5 bosses l2 which are tapped toreceive the bolts used in attaching the housing cast to the frame of theautomobile. An important feature of my electric fuel pump is the factthat this pump can be located at any part on the frame of an 0automobile or other vehicle. I prefer to locate my electric fuel pump atthe rear of the automobile frame adjacent the usual fuel tank, andpreferably my fuel pump is so located that it is not exposed to the heatof the exhaust pipe or gas discharged therefrom. In this manner the mostcommon cause of vapor lock is eliminated. A casing 14 is attached to thehousing I!) as bymeans of screws 16. This casing 14 has connectedthereto One end of the fuel supply pipe 18, which connects the fuel pumpwith the-main fuel I tank of the automobile. The inlet pipe l8 dscharges into the bottom of the casing M which is closed at its lowerend by a cover removably attached to the casing It by means of a screw22. The chamber 24 immediately above the cover '20 constitutes the watertrap of my improved fuel pump, and is sealed against leakage Fuelpassing through screen 26 then passes upwardly through a cylindricalpassage 30 containing a tubular member-32 which is press fittedinto thecylindrical passage 30 of the casing [4. The upper part of the tubularmember 32 is of smaller diameter as indicated at 34, so that when thetubular member 32 is pressed into the passage 30, the valve seat 36 willnot bedistorted.

A disc valve 38 is pressed against the valve seat -36 by a light spring40 which rests on a spider integral with the casing l4. Fuelpassingupwardly through the passage 30 displaces the valve 38 and flowsupwardly through the openings in the spider and then into the diaphragmchamber 5| .piston rod 50. This rod raises the diaphragm and platesagainst the tension of a spring 52,

whose upper end rests against a shoulder- 54,

provided'by the housing I0.

The diaphragm 44 may be made of any suitable material, but I prefer tomake this diaphragm of synthetic rubber strengthened by a reinforcinglayer of fabric embodied in the synthetic rubber. In cold weather wherea normally fiat diaphragm is used the diaphragm becomes stifiened andthe pump requires considerable force initially to flex the diaphragmunder these conditions. In order to reduce the force necessary to startpump operation in cold weather, I provide 'my improved diaphragm with anupwardly projecting, annular groove 56, as most clearly shown in Figs. 4and 5. By-referring to ing upon a support 68' prexed into the upperendright hand end is attached to the armature I4.

Fig. 3, it will be seen that this groove lies just outside of the upperplate 48. The presence of this groove 56 permits the grooved part of thediaphragm to roll upon itself under all positions of the diaphragm andits associated plates 46 and 48. This grooved diaphragm thus substitutesa rolling motion for a stretching or compressing action between parts ofthe diaphragm when it is stifiened due to cold weather, and in thismanner which communicates with the discharge pipe 60 leading to theengine carburetor; The valve 51 is pressed against the seat 62 by aspring 64 rest- .of the cylindrical passage 58. This support 68 hasports to permit the fiow of fluid therethrough. Thelower end 'of'thepassage 58 is closed by a metal cup 12 which is press fitted into thepassage 58, and which prevents direct communication between the chamber24 con.-- stituting the water trap and the dischar e. pipe 60.

The piston rod 50 for raising the pump diaphragm, extends upwardlythrough an opening provided in an armature I4. The piston rod connectedto the armature by means of an adjustmg screw IS, a block 18, and atransverse pin;

80, which forms part of the armature.

The armature I4 is connected toone end of; a spring 82 which forms aflexible pivotal support for the armature. The other of this spring 82is secured between a guide plate :5 andasupporting plate "86. Over-lyingthe spring preventing the creation of sharp bends and undue stressestherein, is a protective plate 88 whose The supporting plate 86 haslaterally extending ears 90 which are secured bymeans of bolts 92" tothe ends of a'U-shaped frame 94, which rests upon a similarly U-shapedshoulder 96, provided by the housing I0. The armature l4 and diaphragm44 are pulled upwardly against the tension of the spring 52 by'anlectromagnet 88 whose core I00 is'riveteddr welded or otherwise attachedto the U-shaped frame 94 as indicated in Fig. 3.

The supporting plate 86 has a depending portion I02 which terminates ina lower horizontal portion I04. The lower horizontal portion I04.

and the upper horizontal portion of the plate 86 have aligned openingsfor receiving the glass tube I06 of the main switch Zwhich controls theflow of electric current through the motor magnet 98. The glass tube I06is secured to the upper and lower portions of the plate 86 by lacquerwhich is applied to adjacent portions of the glass tube and plate 86.When this lacquer dries it securely attaches the glass tube to theadjacent portions of this plate.

Th glass tube I06 is sealed and is filled with an inert gas. This tubecontains a fixed contact I08, and the movable contact IIO, which arebiased towards each other by a spring not shown; thus the contacts I08and H0 are separated by the force exerted by a switch magnet II2 upon anarmature I I4 attached to the movable contact I I0. Several switchstructures suitable for this purpose are disclosed in my priorapplication and need not be described in detail herein.

The switch magnet H2 comprises a smaller coil II6 and a larger coil II8. Each of these co s consists'of the same number of turns of wire, butthe wire used in making thecoil H8 is of larger.

diameterv than that used in making the coil II6. For this reason thecoil II8isof less resistance than the coil 6. The switch magnet is partof a secondary electric circuit including seconda switches A and B, andresistance C.

"- The switch Acomprises a stationary,, resilientof the contact isdetermined by a stop finger I2I.

The contact I20 and stop finger I2I canbe accurately positioned by meansof adjusting screw I23 and nut I25 without detracting. from theresiliency of the mounting of the contact I20. The switch B comprisescontacts I24 and I28 which are normally separated but which are engagedwhenever the armature reaches the bottom of its stroke as indicated inFig. 7.

The contacts I20, I24, and I26 are mounted on an insulating block I28which is attached to the metal plate 86 as by screw I 30. The block I28also carries the resistance C and a resistance N which is connectedacross the main switch Z. The switches A and B may have the structureand mode of adjustment described in my prior application. The contactI22 of switch A is grounded to the automobile frame through the armature"l4 and its supporting means, as indicated at I32 in Figs. 7 through 11.

As indicated in these figures, the automobile has the usual battery I34,grounded to the automobile frame as shown at I36 and connected to theignition switch I38. A conductor I40 connects the latter with contactI08 of the main switch Z. In actual practice the conductor I40 1comprises a wire leading from the ignition switch to the outer end .of abinding post mounted at a convenient placein the wall of the housing I0and a second wire leading from the inner end of the binding post to thelead of contact I08. A second conductor I42 connects the other contactIIO with the motor magnet coil 98 which is ductor I40 and disengagingthe upper end of piston rod 50 from armature pin 80, the frame 84 andall of the mechanism attached thereto may be removed from the housingl0.

A removable cover I44 normally closes the upper end of the housing I0and protects the parts against dirt and water. The housing is providedwith a breather opening I46 which prevents the accumulation of moistureinside the housing. A drain hole I48 carries off the water in case ofatotal submergence of the housing III.

In automotive practice a six volt battery is used but when a weakbattery is used to start an automobile in cold weather, the voltageavailable to operate a fuel pump may drop to three and one-half volts.Ordinarily the carburetor float bowl holds sufficient fuel to start theengine, but in some instances the fuel leaks out of the float bowl andthe fuel pump must furnish the fuel during the starting operation. Theother extreme of voltage variation to which my fuel pump is subjected,is created by the generator for charging the automobile battery. Thisgenerator (not shown) frequently creates as much as nine volts.

In order to be certain that the fuel pump will operate satisfactorilyunder the severest conditions, the automobile manufacturers require thatthe fuel pump start and continue to deliver a satisfactory volume offuel on three volts and at a temperature of ten degrees below zeroFahrenheit. They also require that the fuel pump operate withoutpounding. or thumping on nine volts and at summer temperatures. The pumpdisclosed in this application is capable of meeting these drasticrequirements.

In a typical installation, the motor magnet 98 has a resistance of oneand one-half ohms; the coils I I6 and 8 have resistance of 18 and 15ohms, respectively; and the resistance elements Cand N have resistancesof 15 and 50 ohms, respectively. Coils H6 and H8 each have 1100 turns,the difference in size and resistance being due tothe use of differentdiameter wire. The core I00 of the motor magnet is made of such size andmaterial that it' becomes saturated at six volts, wherefore the forceexerted by this magnet on armature 14 does not increase with highervoltages and pounding and thumping are eliminated.

The arrangement of the coils H6 and H8 and upper end of the casing I4and the adjacent part of the housing I0. It is undesirable to clamp thisdiaphragm too tightly. I therefore provide this part ofthe housing IIIwith an annular flange I50 of such height that the diaphragm is firmly.clamped in place when the upper end of the casing I4 is drawn up intotight engagement with this flange. The provision of this flange makes itpossible to apply the necessary force on the lock washers I52 withoutinjuring the diaphragm 44.

I have obtained the best results when the filter screen 26 is so madethat prior to assembly in the casing I4, the central portion of thisscreen bulges downwardly. After this screen has been assembled as shownin Figure 3, the spring 21 holds the central portion of the screen 26 upin horizontal position and thereby presses the edge of the screen firmlyagainst the shoulder 28 so that no leakage can occur around theperiphery of the screen.

My invention operates in the following manner: When the ignition switchof the automobile is .open the parts assume the positions shown in ll8are connected through resistance C to con-;

ductor I40 and the other ends of these coils are connected to conductorI40 by wire I54 but no current flows through coils -I I6 and H8 at thistime.

resistance C in the secondary circuits is such that maximum power withlow voltage is obtain- .able to break the main switch Z with minimumment also prevents pitting of the contest points of switches A andB.

Other advantages of the circuit arrangements will be apparent from thedescription of the operation of my fuel pump.

Before describing in detail the mode of operation of myinvention, I wishfirst to call attention to several structural features which have notheretofore been sufficiently described. Referring, flrst, to Figures 1and 6, the bosses I2 are shown as extendinglaterally from the housingI0. Where a die-cast housing is used, these bosses I2 will, of course,be an integral part of the casting. Where the housing I0 is stamped, thebosses I2 may be welded thereto, although with a stamped housing III Iprefer to'make these bosses an integral part of the upper end of thecastingcQnstituting the filter casing I4.

In Figure 3, I have shown thepump diaphragm The current flowing throughcoil 98 of the motor magnet energizes this magnet and pulls armature I4upwardly. The grooved diaphragm 44 materially reduces the force whichthe motor magnet must exert in cold weather to start the pump. As thearmature 14 starts its upward,

movement, the contacts of switch B separate, as indicated in Figure 8,thereby breaking the circuit through coil H6.

As the armature 14 moves upwardly it raises the diaphragm 44 against theresistance of spring 52. This causes fuel to enter chamber 24 throughpipe I8 leading from the main fuel tank. Any water entering with thefuel stays in chamber 24, whereas the fuel passes upwardly throughdirt-removing screen 28, past valve 38, and into, the enlarging chamber42 beneath the diaphragm 44.

Just before the diaphragm 44 is stretched taut thecontacts of switch Aengage and ground coil IIE through armature 14, as shown in Figure 9,which indicates the conditions at the instant the contacts of switch Aengage. The resultant energization of the switch magnet attracts thearmature II4 of the main switch Z and opens thisswitch, thereby breakingthe circuit through the motor magnet. The high resistance Nconnected-across the main switch Z reduces arcing at the main switchcontacts. It is to be noted that the full battery voltage is impressedon coil H6 to open the main switch.

Maximumeiiiciency is only possible where the inertia of the fuelentering the diaphragm chamber 42 is utilized to bulge the diaphragm 44upwardly to its fullest extent. The filter parts have been speciallydeslgnedto make this pos-, sible. The chamber 24 and screen 25 are soshaped and arranged that the fluid in the left hand part of chamber 24,as viewed in Figure 3, is quiescent and acts like a solid which does notinterfere with the right angled turn executed;

' movement.

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by the fluid as it enters chamber 24 from pipe I8 and then passesupwardly to the diaphragm chamber 42 by way of passage 30. I In adiaphragm pump of the type which I hav disclosed, the maximumefficiency, quietness,

economy, and smoothness of operation obtain when the timing of the partsis such that the .upward pull of the armature on the diaphragm ceasesjust before the diaphragm is pulled to tautness. This eliminates thewear and tear to which the diaphragm is subjected when it is pulled tautby the armature and thereby greatly prolongs the life of the diaphragm.This also eliminates the vibration and water hammer which are presentwhen the diaphragm is pulled taut by the armature. .When the timing issuch that the central portion of the diaphragm ceases its upwardmovement just before the diaphragm is taut, there is a slight slack inthe diaphragm which hangs downwardly at the instant the central portion'of the diaphragm ceases its upward The inertia of the infiowing fuelswells this slack portion of the diaphragm upwardly and thereby fillsthe diaphragm chamber to maximum capacity. At the same time the inflowof fuel is cut off gradually as the diaphragm is swelled upwardly to itsmaximum extent and this gradual cutting off of the inflow of fueleliminates water hammer.

At the instant the main switch Z opens, the circuit through coil H6 isbroken. Simultaneously therewith, a lesser and more economical currentis established through switch magnet coil H8 which holds th main switchZ open. As shown in Figure 10, this current flows through conductor 14B,resistance C, wire I56, coil H8, Wire $55, conductor I42, and coil 98 toground. This current is not sufiicient to energize the main motor magnetappreciably.

The initial downward movement of armature Hi opens switch A but thisproduces no new result since the circuit through switch A and coil H6has already been broken by the opening of the main switchZ. Continueddownward moveand neutralizes that exerted by coil H8 on armature H4 sothat main switch Z closes due to its own inherent bias and the cycle isrepeated. While coil H8 is potentially more powerful than coil H6, thisis offset by the relative positions of the two coils with respect toarmature. H4. The coils H6 and I iii are shown as wound in oppositedirections. It is more economical as a practical matter to wind thesetwo coils in the same direction and merely to reverse oneof their leadsso that the same result is obtained. While I have illustrated anddescribed a preferred embodiment, of my invention, many fications may bemade without departing from the spirit of the invention, and I do notwish to be limited to the precise details of construction set forth butdesire to avail myself of all changes within the'scope of the appendedclaims.

Having thus described my invention, what I claim is:

1. An eflicient'electric fuel pump comprising a diaphragm, a diaphragmchamber, an electric motor for raising said diaphragm, a spring forlowering said diaphragm, means for cutting out said motor just prior tocompletion of the full upward movement of said diaphragm, whereby fuelentering said diaphragm chamber may bulge said diaphragm upwardly, andfilter means associated with said diaphragm chamber and permitting fuel-to flow thereinto to bulge said diaphragm upwardly, said filter meanscomprising a circular chamber forming a water trap, a screen above saidchamber, and means providing a passageway connecting said last namedchamber with said diaphragm chamber, said water trap chamber having aninlet adjacent said passage.

2. An eflicient low power fuel pump of the class described, comprising adiaphragm, a diaphragm chamber having a fuel inlet and a fuel outlet, anelectric motor for raising said diaphragm, a. spring for depressing saiddiaphragm, said diaphragm having an annular upwardly projecting grooveformed therein to reduce the resistance to movement of said diaphragm atlow temperatures, said motor includinga magnet having a core and a coil,said coil being adapted for connection to a source of current having avariable voltage, said core being of such size and material that it ismagnetically saturated ata voltage lower than the maximum voltage ofsaidsource, and switch means alternately connecting and disconnectingsaid motor from said source.

3. an enicient electric fuel pump of the class described, comprising avariable chamber, an electric motor connected to a movable wall of saidchamber for increasing the size of .said chamber, a spring for movingsaid wall to decrease the size of said chamber, said chamber having afuel inlet and a fuel outlet, a main switch for said motor,-said mainswitch including a movable contact provided with an armature, a magnetcore for attracting said armature to open said switch and hold it inopen position, means for magnetizing said core to one degree to opensaid switch .'and means for magnetizing said core to a less degree tohold said switch in open pasn.

4. An effieient electric fuel pump of the class described, comprising avariable chamber, an electric motor connected to a movable wall of saidchamber for increasing the .size of said chamber, a springfor movingsaid wall to decrease the size of said chamber, said chamberhaving afuel inlet and a fuel outlet, a main switch for said motor, said mainswitch including a movable contact provided with an armature, a magnetcore for attracting said armature to open said switch and hold it inopen position, a coil surrounding said core, means for. establishing arelatively high resistance circuit through said coil, and means forestablishing a relatively low resistance circuit through said coil. 5.An efiicient electric fuel pump of the class described, comprising avariable chamber, an

electric motor connected to a movable wall of saidchamber for increasingthe size of said chamber, a spring for moving said wall to decrease thesize of saidchamber, said chamber having a fuel inlet and a fuel outlet,a main switch for said motor, said main switch including 'a movablecontact provided 'with an armature,

I a'magnet 'core'for attracting said' armature to open saidswitchand'hold it in open position, a pair of coils surrounding said core,said coils being capable of electrically opposing each other,

and means for establishing electrical circuits through said coils tocontrol said switch.

6. An eilicient electrical fuel pump of the class described, comprisinga variable chamber, an

electric motor connected to a movable wall of said chamber forincreasing the size of said chamber, a spring for moving said wall todecrease the size of said chamber, said chamber having a fuel inlet anda fuel outlet, a main switch for said motor, said main switch includinga movable contact provided with an armature, a magnet core forattracting said armature to open said switch and hold it in openposition, a pair of coils surrounding said core, one of said coils beingof less resistance than the other, and means for establishingelectrical-circuits through said coils to control said switch.

"7. An efficient electric fuel pump of the class described, comprising avariable chamber, an electric motor connected to a movable wall of saidchamber for increasing the size of said chamber, a spring for movingsaid wall to decrease the size of said chamber, said chamber having afuel inlet and a fuel outlet, a main switch for said motor, said mainswitch including a movable contact provided with an armature, a magnetcore for attracting said armature to open said switch and hold it inopen position, a pair of coils arranged in tandem about said core, saidcoils having the same number of turns of wire, but the core farthestfrom said switch being 8. An efiicient electric fuel pump comprising adiaphragm, a diaphragm chamber, an electric motor for moving saiddiaphragm in' one direction, a spring for moving said diaphragm in theopposite direction, means for cutting out said motor just prior tocompletion of one full movement of said diaphragm, whereby fuel enteringsaid chamber may bulge said diaphragm to its fullest extent, and filtermeans associated with said diaphragm, chamber and permitting fuel toflow thereinto to bulge said diaphragm, said filter comprising a chamberforming a water trap, a screen interposed between said last namedchamber and said diaphragm chamber, outlet means connecting said watertrap chamber with said diaphragm chamber, and inlet means for said watertrap chamber.

' 9. An efficient electric fuel pump of the class described, comprisinga diaphragm, a diaphragm chamber, an electric motor for moving saiddiaphragm in one direction, means for moving said diaphragm in theopposite direction, switch means for cutting out said motor. just priorto completion of a full movement of said diaphragm, whereby fuelentering said diaphragm chamber may bulge said diaphragm to the limit ofits movement, and filter means associated with said diaphragm chamberand permitting fuel under its own inertia to flow thereinto to bulgesaid diaphragm, said filter means comprising a water trap chamber, inletmeans communicating with said water trap chamber at one side thereof,and outlet means connecting said water trap chamber with said diaphragmchamber, said outlet means communicating with said water trap chamber ata right angle to said inlet means.

10. An efiicient electric fuel pump comprising a diaphragm, a diaphragmchamber, an electric motor for moving said diaphragm in one direction,other means for moving said diaphragm in the opposite direction, meansfor cutting out said motor just prior to completion of a full movementof said diaphragm, whereby fuel entering said diaphragm chamber maybulge said diaphragm to one limit of its movement, and filter meansassociated with said diaphragm chamber and permitting fuel to fiowthereinto under its own inertia to bulge said diaphragm, said filtermeans comprising a water trap chamber having a part forming a dead spacein which the liquid contents is quiescent, and another part connectedwith inlet and outlet means for fuel entering and leaving said chamber.

11. An efiicient low power fuel pump of the class described, comprisinga non-metallic diaphragm, a diaphragm chamber having a fuel inlet and afuel outlet, an electric motor for moving said diaphragm in onedirection, a spring for moving said diaphragm in the opposite direction,said diaphragm having an annular groove formed therein to reduceresistance to movement of said diaphragm at low temperatures, and switchmeans alternately connecting and disconnecting said motor with a sourceof current.

12. In a fuel pump of the class described, the combination of adiaphragm chamber, a diaphragm, an electric motor for operating saiddiaphragm, switch means for controlling said motor, a housing enclosingsaid motor and switch means, said housing including an internalshoulder, and a frame removably resting onsaid shoulder and having saidmotor and switch means unitarily attached thereto.

13. In a fuel pump of the class described, the combination of adiaphragm chamber, a diaphragm, a motor for operating said diaphragm, afilter casing providing a circular chamber forming a water trap, acircular passage extending upwardlyfrom said water trap to saiddiaphragm chamber and constituting a fuel inlet for the latter, a secondtubular passage leading down? wardly from said diaphragm chamber andforming an outlet for the latter, means cutting oif communicationbetween said last named passage and said circular chamber, said casingproviding a shoulder at the upper end of said circular chamber, a screendistorted into disc shape and thereby pressed firmly against saidshoulder, a spring holding said screen in such distorted condition, anda removable closure for said circular chamber, said closure forming asupport for said screen.

14. An eflicient low power fuel pump of the class described, comprisinga diaphragm, a diaphragm chamber having a fuel inlet and a fuel outlet,means including an electric motor for operating said diaphragm, a switchcontrolling said motor, a pair of coils for opening said switch, acircuit arrangement operative at one phase of motor operation to makesaid coils of substantially equal value, and a. second circuitarrangement operative at another phase of motor operation to make saidcoils of unequal value.

JOHN B. wnrrrno,

